JP2004199184A - Optical reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive optical reading device using an LED for a light source wherein luminance non-uniformity is reduced or eliminated. <P>SOLUTION: An illuminating device having a light source for emitting lights to an object is provided with a plurality of LED 3, an LED substrate 7 on which those LED 3 are arranged with intervals, a case for fixing the LED substrate 7 and a cylindrical lens arranged in the case for converging spread emitted lights emitted by the LED 3 to parallel lights. The LED substrate 7 is formed with a land 9 formed through an insulating part 10 in the periphery of the LED 3 for reflecting the emitted lights from the LED 3. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical reader. More specifically, the present invention relates to an improvement in the structure of an optical reading device that irradiates a subject such as a card, a check, and a passbook with light to capture an image.
[0002]
[Prior art]
2. Description of the Related Art An optical reading device that irradiates a subject with light, collects reflected light on a light receiving element, and captures an image is used (for example, see Patent Document 1). For example, in a device that reads barcodes, characters, and the like, it is common to use a light source that emits infrared light to separate dirt and characters to be read from the background. In addition, depending on conditions such as the type of ink of the read character, the color of the ink used for the background of the read character, and the use of the optical reader, use of light other than infrared light may be appropriate. There are various reading devices such as those using a red LED and those using a white fluorescent tube.
[0003]
When a red LED is used, the red LED itself is inexpensive and the cost of the apparatus is lower than that of a fluorescent tube, but red may be a dropout color and red characters may not be read. For this reason, when the red LED cannot be used, a reading device using a white fluorescent tube which is less affected by a dropout color has been provided.
[0004]
In recent years, white LEDs have been manufactured and applied to optical products, and readers using white LEDs instead of white fluorescent tubes have also been manufactured. Since white LEDs have high brightness and are easy to achieve miniaturization, they are suitable as a light source in an optical reader in these respects, but they are still expensive and are difficult to use as many as inexpensive red LEDs. is there.
[0005]
[Patent Document 1]
JP-A-6-318734
[Problems to be solved by the invention]
However, since a plurality of red and white LEDs are arranged at intervals, the light illuminating the subject is not a single uniform light beam like a fluorescent tube, but only the LED portion is a light beam with bright illumination unevenness. Become.
[0007]
Therefore, an object of the present invention is to provide an optical reader that is inexpensive while using an LED as a light source, and that reduces or eliminates uneven illuminance.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the invention according to claim 1 is directed to an optical reading device that irradiates light from a light source to a subject and collects reflected light from the subject to a light receiving element via a lens. A lighting device provided with a light source for irradiation includes a plurality of LEDs, an LED board having the LEDs arranged at intervals, a case for fixing the LED board, and a diffused irradiation provided by the LEDs arranged in the case. A cylindrical lens that converges light into parallel light, and a land formed on the LED substrate through an insulating portion around the LED and reflecting irradiation light from the LED. It is.
[0009]
In this optical reader, the land formed on the LED substrate reflects the light emitted by the LED, so that more light can be applied to the subject. For this reason, it is possible to maintain or reduce the number of LEDs while securing a necessary and sufficient amount of light as an optical reading device, and it is possible to reduce costs accordingly. In this case, the LEDs are arranged at intervals, and further reducing the number of points may cause illuminance unevenness. However, according to the lands formed on the LED board, when the light is reflected, It is possible to reduce or eliminate unevenness in illumination by reducing bias.
[0010]
The invention according to claim 2 is characterized in that the lands are formed by solder. According to the solder, the land can be formed at low cost. Also, lands of various shapes can be formed according to the specifications, the number of installation points, the arrangement, and the like of the LEDs.
[0011]
The invention according to claim 3 is characterized in that the LED is a white LED. A white LED is suitable as a light source for an optical reading device because it has high luminance and can easily be miniaturized. Moreover, according to the present invention, it is possible to maintain or reduce the number of LEDs while securing a necessary and sufficient amount of light by the land, so that the cost can be reduced accordingly.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.
[0013]
1 to 4 show an embodiment of the present invention. The optical reader 1 according to the present embodiment irradiates a subject 4 with light emitted from a light source 3, condenses the reflected light on a light receiving element 6 via a lens 5, and captures an image of the subject 4.
[0014]
The lighting device 11 including the light source 3 includes a plurality of white LEDs (hereinafter, referred to as “white LEDs 3” in the description of the present embodiment) as the light sources 3 and an LED substrate 7 on which the white LEDs 3 are arranged at intervals. A case 2 for fixing the LED substrate 7; and a cylindrical lens 8 disposed in the case 2 and for converging diffused irradiation light emitted from the white LED 3 to parallel light (see FIG. 3). On the LED substrate 7, lands 9 are formed around the white LEDs 3 via an insulating portion 10 and reflect the irradiation light from the white LEDs 3, and the lands 9 are hatched in FIG. Shown). Further, the optical reader 1 of the present embodiment includes a glass plate 12 for transmitting the irradiation light from the white LED 3, and a reflecting mirror 13 for changing the direction of the light reflected on the upper surface 4 a of the subject 4 to a direction in which the lens 5 is located. A lens 5 for condensing the light reflected by the reflecting mirror 13, and a CCD 6 as a light receiving element for converting a light beam from the lens 5 into an electric signal. The subject 4 from which an image can be captured is, for example, a card, a check, a passbook, or the like.
[0015]
In the present embodiment, a white LED 3 that can obtain high luminance is used as a light source. However, since the white LED 3 is generally expensive, it is preferable that the score be as small as possible within a range where a necessary and sufficient amount of light is obtained in order to reduce the cost. In the present embodiment, a plurality of, for example, six white LEDs 3 are evenly arranged in a line on the LED substrate 7, and a light reflecting portion (in this specification, this is referred to as “ A land is indicated by reference numeral 9) to compensate for the amount of light (see FIG. 1). The land 9 is preferably made of a material having a high reflectivity capable of reflecting light more efficiently. In the present embodiment, the land 9 is formed by forming a pattern using solder, which has high reflectivity and is low in cost. According to the solder, a higher reflectivity can be achieved than when a white resist is used as the reflecting material, for example. Further, the white resist is harder to make than the land 9, but in the present embodiment, since the land 9 is formed using solder, the work becomes relatively easy. When relatively soft solder is used, the white LED 3 can be easily formed into various shapes according to the specifications, the number of installation points, the arrangement, and the like. The surface shape of the land 9 may be, for example, a concave shape that easily converges reflected light. However, when the solder is selected as the material of the land 9 in this way, it is necessary to provide the insulating portion 10 between the white LED 3 and the land 9 in order to maintain the insulation with the white LED 3. For example, in the case of the present embodiment, a gap having a certain width or more is formed between the white LED 3 and the land 9 to form the insulating portion 10 (see FIG. 1).
[0016]
The glass plate 12 is fixed to a medium guide portion 2 a outside the case 2 formed to project toward the medium passage so as to be located between the white LED 3 and the subject 4. The reflecting mirror 13 is attached to an upper portion 16 a of a bracket 16 fixed to the case 2 with screws 15. The upper portion 16a of the bracket 16 is bent at an appropriate angle toward the lens 5 so as to direct the reflected light from the medium upper surface 4a toward the lens 5. The lighting device 11 is fixed to the case 2 by a holder 17. The holder 17 is fixed to the inside of the case 2 of the optical reader 1 with screws 14 (see FIG. 2). A stop 23 for reducing the amount of reflected light is provided in front of the lens 5.
[0017]
The control device of the optical reader 1 controls an image signal from the CCD 6, and includes an amplifier 18, an A / D (analog / digital) converter 19, a shading processing circuit 20, a halftone processing circuit 21, It comprises a white reference memory 22 (see FIG. 4). The shading processing circuit 20 determines the image signal from the A / D converter 19 based on the white reference level in the white reference memory 22, and shades a portion having a higher reflectance than white exceeding the white reference level as white. Make corrections. The halftone processing circuit 21 performs pseudo halftone processing (binarization processing) and moire removal. The white reference memory 22 stores a white reference level corresponding to shading by the white LED 3. In this embodiment, a line type CCD is used as the CCD 6.
[0018]
The operation of the optical reader 1 according to the present embodiment configured as described above will be described below.
[0019]
When the subject 4 passes through the medium passage and is transported to the vicinity of the medium guide 2a, a sensor (not shown) detects the subject 4. Upon receiving this detection signal, the white LED 3 emits light.
[0020]
The irradiation light from the white LED 3 passes through a condenser lens (not shown) provided at the lower end of the illumination device 11 and the glass plate 12 and is reflected on the medium upper surface 4a. The reflected light is reflected by the reflecting mirror 13 and then enters the CCD 6 along the optical axis of the lens 5 to be converted into an electric signal. The image signal converted by the CCD 6 is amplified by an amplifier 18, A / D converted by an A / D converter 19, and subjected to shading correction in a shading processing circuit 20. The image signal from the shading processing circuit 20 is subjected to pseudo halftone processing (binarization processing) and moire removal by the halftone processing circuit 21. As a result, images such as ink characters and bar codes formed on the medium upper surface 4a are read and captured as data.
[0021]
The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, the preferred optical reading device 1 using the white LED 3 as the light source is shown, but an LED other than white may be used.
[0022]
Although the land 9 has been described as being made of solder, this is merely a preferred example, and the land 9 may be formed of another material or material such as a reflecting material such as a mirror.
[0023]
【The invention's effect】
As is apparent from the above description, according to the optical reading device of the first aspect, the land formed on the LED board reflects the light emitted by the LED, so that more light can be applied to the subject. For this reason, it is possible to reduce the number of LEDs while securing a necessary and sufficient amount of light as an optical reader, and it is possible to reduce the cost accordingly.
[0024]
According to the optical reading device of the second aspect, the land can be formed at low cost by soldering. Also, lands of various shapes can be formed according to the specifications, the number of installation points, the arrangement, and the like of the LEDs.
[0025]
Further, according to the optical reading device of the third aspect, since the white LED is used, a bright and bright light source can be provided. In addition, it is possible to maintain or reduce the number of LEDs while securing a necessary and sufficient light amount depending on the land, so that the cost can be reduced accordingly. Therefore, it is possible to use inexpensive white LEDs.
[Brief description of the drawings]
FIG. 1 is a view showing one embodiment of the present invention, and shows an LED substrate in which a land is formed around a white LED via an insulating portion.
FIG. 2 is a plan view of the optical reader according to the embodiment.
FIG. 3 is a sectional view of the optical reader shown in FIG. 2, taken along the line III-III.
FIG. 4 is a block diagram illustrating a configuration of a control device.
[Explanation of symbols]
1 optical reader 2 case 3 white LED (light source)
4 Object 5 Lens 6 Light receiving element 7 LED board 8 Cylindrical lens 9 Land 10 Insulating part 11 Lighting device

Claims (3)

In an optical reading device that irradiates light from a light source to a subject and collects reflected light from the subject to a light receiving element via a lens, an illumination device including a light source that irradiates the subject includes a plurality of LEDs. An LED board in which these LEDs are arranged at intervals, a case for fixing the LED board, and a cylindrical lens arranged in the case and for converging the illuminating light emitted by the LED and diffusing to parallel light. An optical reading device, wherein a land is formed on the LED substrate around the LED via an insulating portion and reflects a light emitted from the LED. The optical reader according to claim 1, wherein the lands are formed of solder. The optical reader according to claim 1, wherein the LED is a white LED.

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